csrutil disabled but still unable to change previlages

Here are two Apple articles regarding the changes to the drive layout beginning with macOS 10.15 and further changed in macOS 11.x+ which prevents anyone from modifying items within the macOS system area:

About the read-only system volume in macOS Catalina or later - Apple Support

Signed system volume security in iOS, iPadOS, and macOS - Apple Support

There is no need to write to the system area. If you want full control of the system, then you are using the wrong OS.

dwijeshbharadwaj wrote:

I disabled csrutil, rebooted in recovery mode, and then checked the status. It's off, but now, when I try to change the privileges on the Macintosh HD or the System folder in my Mac to give read and write permission to myself or add me, I don't have permission.

No, you don't. Neither does anyone else any more.

Is there anyone at Apple who can solve this problem

No. To contact Apple, Contact Apple.

dwijeshbharadwaj wrote:

This is absurd. It's my computer, and I can't change privileges, but there is no support for this, not anywhere on the internet. Is there anyone at Apple who can solve this problem

FWIW, it is your computer but you lease the operating system.

What are you trying to change permissions on exactly?